The invention relates to manufacturing apparatus and methods for the assembly of precisely constructed flexible disk record storage structures.
As data processing systems become more demanding, the compact storage of digital data signals with relatively rapid access is becoming a more important feature of data processing systems. The storage and access of data bases is becoming a more monumental problem. To enhance data processing systems, record storage apparatus such as shown in U.S. Pat. No. 3,940,794, have been invented. Such apparatus provides good compactness while enhancing (reducing) access time. The apparatus employs flexible record storage disks such as disks having a Mylar substrate. Such substrates are subject to solid flow conditions. That is, during the assembly and after the assembly, the precise shape of the record storage disk may change. Such changes normally are considered insignificant. For example, the magnitude of such changes in the assembly due to temperature and pressures and so forth, may be a small portion of a millimeter. However when such material is used in connection with digital data storage, such apparent minute changes become significant. At several hundred tracks per centimeter, such changes may be several track widths -- making track location difficult.
Such digital data storage apparatus may employ 60 tracks per centimeter. A transducer is positioned with respect to a given track by a so-called track following servo mechanism. Such servo mechanisms are subject to error by perturbations in the concentricity of the record storage tracks. That is, if the record storage track is off-center with respect to the true axis of rotation, either the servo mechanism for track following does not follow the track precisely resulting in data errors, or the cost of the data storage apparatus can be inordinately increased. Accordingly, it is extremely important that the flexible record storage disks be precisely concentric with the axis of rotation of the stack of disks for facilitating faithful storage and reproduction of digital data signals. The same criteria of course, also applies to image data storage systems.
A disk storage structure for achieving the concentricity required above, is set forth in commonly assigned copending patent application Ser. No. 564,406, Griffiths et al, filed Apr. 2, 1975, and now U.S. Pat. No. 3,969,767. In the latter application, the flexible storage disk structure consists of a flexible record storage member having a cold flowable substrate such as Mylar film suitably attached to a center semi-rigid ring support member. The ring supports are faced together to form a laminated tubular spindle for supporting a stack of disks as shown in the latter referenced patent application. The flexible record member and a center support ring member must be coaxial to ensure concentricity of the record tracks with respect to the axis of rotation.